Variable load brake



June 26, 1945. S G. DOWN ET AL 2,379,285

VARIABLE LOAD BRAKE Filed Nov. 5, 1942 ATTORNEY Patented June 26, 1945UNITED gSTATES PATENT ortica 2,379,285 l l VARIABLE LoAn kBRAKE y SidneyG. Down, Edgewood, andCklydeI Farmer, Pittsburgh, Pa., assignors toTh'eWestinghouse Air Brake Company, Wilmerding, Pa., a corporation ofPennsylvaniak .16 Claims.

v,This invention relates to railway vehicle brake apparatus and moreparticularly to variable load brake rigging of the typel in which theleverage may be automatically varied in accordance with variations inthe weight of the load on'the vehicle to correspondingly vary the forcewith which the brake is adapted to be applied.

yAn object of the invention is to provide an improved variable `,loadbrake apparatus of the above mentioned type. i Another'obje'ct of theinvention is to provide a variable jload brake rigging of the abovemen-v tioned type which is so constructed and arranged that it will beautomatically conditioned. or changed over for either empty or loadbraking by fluid under pressure from the usual lfluid pressure operatedbrake cylinder upon initiating an application of the brakes. l

A lfurther object of the invention is to provide automatically'operative means for automatically and positively locking the rigging inany of its conditioned positions when initiating an application oithebrakes and for automatically unlocking the rigging when effecting arelease of the brakes.

Otherobjects and advantages will appear in the following detaileddescription.

In the accompanying drawing Fig. 1 is a fragmentary diagrammaticvertical sectional view taken longitudinally of. a railway vehicletruclr embodying the invention, parts of the truck and of the brakerigging, 'not necessary yfor a clear understanding 'of the invention,being omitted. Fig. 2 is a fragmentary diagrammatic vertical sectionalview of a portion o f the railway vehicle truck shown in Fig.l and lof amodified brake conditioning means which may be employedin lieu of theconditioning meansv Shown in Fig. 1. `]n"flllig. l of the drawing, thevariable load brakefrigging is shown applied to a railway vehicle truck.which may be of the usual well 5' ofthe usual ivell'kno'wn type havinga cylinder B which Ais 'mounted on anV un'sprung part of the vehiclesuch asaztruck side frame'iand which contains the usual piston'(notfshown) having a push rod .'I` which projects beyond one end of thecylinders. l The outer end of the push rod 'l is -operativelyconnectedto one end of a vertically disposedfbrakecylinder lever 8 by means of apin 9.

The pin 9, inaddition to connecting the adjacent ends of lever 8 andpush rod 'I together, also carries a roller -lll which is adapted totravel in a guide'slot H1 provided in avbracket I2 carriedby an unsprung-part of the vehicle, such for example asga truck side kframe, lthusthe' bracketsupportsthe lever. f l

f Theoppositeend of the brake cylinder lever 8 is operatively lconnectedto one end of `a longitudinallyextendrlg pull rod I3. The opposite endof this pullrodrris connected to a transversely extending bar M which isoperatively connected at each end with one end of a verticallydisposedlive-.lever I5 preferably arranged in the plane ofy the tread oithe adjacent Wheel of the Wheel assembly lat one end of the truck.r Eachlive lever I5 has operatively connected thereto, intermediate its ends,a brake shoe I6 which is adapted to bemoved into and out of frictionalbraking engagement with a wheel. The opposite ends of the live' leversl5 maybe operatively connected togetherr by means of a laterallyextendingbarl'l.- v i. i Beyond the Wheel assembly at the other end ofthe truck the'brakefrigging may comprise apair of vertically disposeddead brake levers which may be arranged in the plane of the tread of awheel of the assembly, which levers may be ful- Civ crumed at one `endto the truck frames, and which may be operatively connected together attheir opposite ends by means of transversely eX- tending barswhichV maycorrespond to the bars I4 and I'Ij. Each brake lever has operativelyconnected thereto, intermediate its ends, a brake shoeforrl` engagementwith the adjacent wheel. This arrangement of brake levers, brake beamsand brake shoes is so well known in the brake art that an illustrationthereof is deemed unvnecessary. r The transversely extending bars vatthis end of the truck are operatively connected together by means oflaterallyspaced longitudinally extending pull rods I8, only one of whichrods is shown.

Rigidly attached to the spring plank 3 and extending upwardly from oneside kthereof is a bracket Zll which carries a pin 2| upon which ispivotally mounted the inner end of afulcrurn lever 22. The opposite endof the lever 22 is connected by means of a pin 23 to one end of averticallyv disposed upwardlyextending serrated or toothed locking bar24 which is slidably guided in a portion 25 carried by the bracket I2.

The fulcrum lever 22 adjacent the outer end thereof carries a pin 26which pin passes through a slotted opening 2B formed in the brakecylinder lever 8 intermediate its ends, which pin serves as a fulcrumfor the brake cylinder lever 8, the slotted opening extendinglongitudinally of the brake cylinder lever.

At one side of the pin 26 the brake cylinder lever 8 is provided with alug 29 to which one end of a coil spring 30 is secured. The opposite endof the spring 3I| is connected to a lug 3| which projects upwardly from`thefulcrum lever 21. This spring, at all times, biases the lever 22 andthereby the pin 23 toward its uppermost position in the slotted opening28.

For shifting the lever 22 and thereby the pinv 26 relative to brakecylinder lever 8 within the slotted opening 28, so as to provide ahigher leverage ratio for a loaded car than for an empty car, and formaintaining the lever and thereby the pin in its adjusted position, acombined adjusting and locking mechanism is provided.

The combined adjusting and locking mechanisrn 35 comprises a bodyportion 36 which may be carried in any suitable manner by the truckbolster 2. Contained in this body portion is a piston 38 having a stem39 which extends to the 'exterior of the casing. The piston stem 39 isslidably associated with thefulcrum lever 22 by means of a link 40 whichis pivotally connected to the stem and which has at its lower end a jawportion 4I provided with slotted openings 42 through which a pin 43carried by the lever passes.

At one side of the piston 38 there is a chamber 45 which is in constantopen communication with a passage and pipe 46, lwhich pipe is connectedto a exible hose` 41 leading to the brake cylinder pipe 10 which may berigidly attached to the brake cylinder and truck frame. The exible hoseis provided for the purpose of accommodating relative movement betweenthe pipe 10 and the truck bolster.

At the opposite side of the piston 38 there is a chamber 49 andcontained in this chamber and interposed between the piston and thelower inner wall of the chamber is a spring 50, which tends, at alltimes, to urge the piston 38, stem 39 and connected link 40 in adirection away from the lever 22.

Clamped between the body portion 36 and a cap portion 5I is a flexiblediaphragm 52. At one side of this diaphragm there is a chamber 53 whichis normally connected through a passage 54 in a wall of the body portion36 to the chamber 49.

At the opposite side of the diaphragm there is a chamber 55. Containedin this chamber and secured in any suitable manner to the diaphragm is adiaphragm follower 56 having a stem 51 which extends to the exterior ofthe cap portion 5I. Also contained in chamber 55 and interposed betweenthe diaphragm follower 52 and the inner wall'of the cap portion is aspring 58 which tends, at all times, to urge the diaphragm 52 in adirection toward the body portion 36 and thereby biases the diaphragmfollower 56 and connected stem 51 inthe same direction.

The outer end of the stem 51 is pivotally connected to one end of a linkmember 60 by means of a pin 6I, which link, at its opposite end, is

pivotally connected to a slidably mounted locking member 62 by means ofa pin 64. This slidably mounted locking member 62 is provided with teeth65 which are adapted to be moved into and out of locking engagement withthe teeth ofthe locking bar 24 hereinbe'fore mentioned. l

It is obvious thatany variation in the position of the fulcrum pin 26with relation to the brake cylinder lever 8 within the slotted opening28 will result in a variation in the leverage of the brake rigging andthereby a variation in the braking power of the brake rigging.

If the fulcrum pin 26 is moved longitudinally ,of the lever in adirection away from the brake cylinder push rod 1 the arm of the brakecylinder lever 8 to which the push rod is connected, will becorrespondingly lengthened in effect so that when the brake cylinder isoperated the power transmitted by the opposite end of the lever to thepull rod I3 will be correspondingly increased. If the pin is moved inthe direction toward the push rod 1 the effective length of the arm isreduced and as a consequence power transmitted from the lever to thepull rod will be decreased.

Operation Assuming the vehicle, embodying the invention, to be empty andthe brakes on the vehicle released. Under these conditions Athe severalparts of the apparatus will be in the position illustrated in Fig. l ofthe drawing and as a consequence the rigging will be in position forempty braking.

When it is desired to effect an application of the brakes fluid underpressure is supplied in the usual well known manner to a brake cylinderpipe 10 which pipe is connected to the brake cylinder 5. Fluid underpressure supplied to pipe 10 flows therefrom to the brake cylinder 5 andalso to the chamber 45 in the combined adjusting and lockingmechanismv35 by Way of the hose 41 and connected pipe and passage 46.Fluid under pressure thus supplied to chamber 45 and acting on piston 38in opposition to spring 5! causes the pistonto move in a downwardlydirection, from the position in which it is viewed in the drawing.

"I'he piston as it thus moves causes the piston stem 39 andconnectedlink 40 to move in the same direction, the link 40, by reasonof the slotted opening 42 in the link, moving relative to the pin 43.This downward movement of the piston, stem and link, continues untilbrought to a stop by a stop member 1 I, carried by the stem, engagingthe casing.

It should here beV understood that when the vehicle is empty, the truckbolster 2 will be in its normal or uppermost position as shown, so thatwhen an application of the brakes is initiated and uid under pressure issupplied to chamber 45 in the manner above described, the piston 38 canmove its full stroke, i. e., to the position just described, before thepin 43 carried by the lever 22 will engage the upper end of the slot 42in the link 40. From this it will be seen, that when the vehicle isempty, operation of the piston 38 will not eifect movement of the lever22 and, the spring 30 will act to maintain the lever 22 and thereby thefulcrum pin 26 in the position shown.

It should here be mentioned that the spring 50 opposing downwardmovement of piston 38 has a low pressure Value, thus a slight increasein uid under pressure in chamber 45 will cause the stem A39.

piston, piston stem and-link to move downwardly and that -this downward-movement will occur before any appreciable 4 brake cylinder pressurehas been developed inthe brake cylinder.

'When the piston L38 -isbrought to a stopbythe stop member H engagingthe casing, the piston will have moved to a position where the vupperface ythereof 'iS v just below ythe passage f54." With the piston inthis position, Athe passage 154 4will establish communication ibetweenchamber '45 and l5,3 (so that fluid under pressure l in chamber 4 5 willflow by way of passage -54 to chamber y53. Fluid u nder pressurethus-supplied to chamber 53 and acting o n diaphragm '5 2 vwillcauseth'e diaphragm jto -flex in la direction Ytoward the lefthand, aslviewed in the drawing, against'the opposing -pressure of the spring 58. Flexing of the diaphragm in this direction will cause the diaphragmfollower-56, stem 57, and link Alill to move in the same directionthereby causing the connected lockingportion l62 to move so that ,theteeth65 thereof vinterlock with 'the teeth of 'the bar 24, thus lockingthe bar 24and lever 2 2 and therebythe lfulcrum pin 26 in position atthe upper end of the slotted opening 23 in the brake cylinder levertuntil such `time as Ythe lbrake cylinder pressure is again depleted ofduid under pressure. -It should here be mentioned that the spring -58lis -of such a value that -it will yield to the power transmitted by Athe ydiaphragm before the pressure of -fluid in the brake cylinderdevice is suiciently high to effect movement of 'the bra-ke cylinderpush rod in its vbrake applying direction. v

After Ithe mechanism h as vbeen locked as just described pressure offluid in the brake cylinder will continue to be increased s o as tocause vthe brake cylinder to function to operate the brake cylinderlever 8 and thereby-the operatively associated connected 'leversandrods'of the brake rigging to move the vbrake lshoes t6 into IbrakingAengagement vwith the treads -of the truck wheels. To initiate a releaseof the brakes, fluid under pressure is vented from thebrake cylinderdevice 'tothe atmosphere by way of pipe "Hl inthe usual manner causing`the brake cylinder device and the connected brake cylinder lever 18 tooperate in kthe -usual well known manner to effect la release of thebrakes.

final releasezof yfluid'under,pressure ...from chamber 53 to vtheatmosphere is :by wayof -passage f54,

chamber 49, and passage185.

Assuming -now that, 4while the brakes are released ladingvis placedyonthe body-ofsthe ivehicle. Under vthe influence of the additional-weight which the lading `vimposeslon the truck bolster 2 of eachtruck,`the bolster springs4 will yield and permit the bolsterto movedownwardly relative to the spring plank 3 and the truck frames (notshown). f l

Since the combined adjusting `and locking mechanism 35 is carriedby thebolsterit will move bodily with the bolster relative tothe spring plank.Upon suchmovement the piston '38 stem 39 and vlink 40- comprising -apart thereof are caused to move relativeto the pin 43 carriedby the1ever'22, such movementbeing accommodated by the slot'42 in the link:40. 'As this movement continues theclearancebetween the upper end ofthe slot 42 and the pin 43'is reducedto adegree proportionateto the loadimposed on the body of the vehicle.

Now vwhen an application of vthe 'brakes is initiated the pistonfsteml39,.,ar1dflink 4 Dfwill be caused to move downwardly to the .stoppedposition in the same manner as hereinbefore described in connection withempty vehiclebraking. Since the clearance between the end ofthe slot 42and theepin 43 has been reduced due to relative movement between thebolster and the spring plank, downward movement of the piston will causethe pin42 to engage the upper endof the slot 42 -in the -link 40 beforethe piston'completes its full travel. Now after the pin 43 engages theupper end of the slot in the link 40-continued movement Aof the pistonin this direction causeslthe lever 22 to rock about the pivot pin 2| ina counter-clockwise direction. As the lever 22 rock-sin this directionit carries the fulcrum pin 26 and locking bar 24 with-it therebyautomatically adjustingthe pin 26 relative to the brake cylinder lever'l'to provide for'the degree of braking called for `by-the weight of thelading carried by the vehicle.

When -the piston 38 :has completed its rtravel the proper adjustmentwill/have been madeand the -piston will again be in a position toestablish communication between chambers-d5 -and v53 so `nism 35isreduced by way of pipe-and passage 46 and lflexible hose 41. Whenafter the pressure of fluid `in pipe 10 and in the brake cylinder device'has lbeen reduced suiciently to effect the @release of the brakes, 4thepressure in chamber '53 reduces vtoa slight degree' below the 'opposingpressure yof `the spring E58, the spring acting through the medium -ofthe diaphragm follower 156, follower stem l 5 1 and link 60 will move`the ylocking member l-65 out `of :locking Aengagement with Ithe toothedlocking bar 24 thus unlocking fthe 'lever -22 and thereby-fulcrumpin'26. When the-pressure lin chamber 45 has-been reduced suflicientlythe spring SI1-will acttoreturnthe piston 38 stem -38 and link 40 to therposition -in which vlthey are shown inthe drawing. 'It will here benOted'that when the-piston v38 returns to the'pos'imay be substitutedfor the combined 'adjusting' that 'the combined adjusting andlockinglmechanism caused to shift' the fulcrum .pin 26 to its adjustedpositionand to lock it in this position -in the same manner as before describedin connection with'emptybraking. v

As the uidu'nder pressure in the brake cylinder 5 is increased, Ithedevice will function in the same manner as already described inconnection with empty braking to effect 'an application of the brakes onthe vehiclef f When it is desired to effect a=release of v:the

brakes fluid under pressure is vented 'from Athe brake cylinder pipe 1Gand `as a consequencethe brakes are released and :the fulcrum -pin 25re-` turned to the position in which it is maintained by the weight ofthe load Ycarried by the vehicle in identically the samemannerhereinbefore described in connection with. a release `of the brakes onan empty vehicle. V Dmcription of combined adjusting cmd lockingmeclmmsvmshoum Eig. 2 I

.ln Fig. 2 there is lshown another form' of com:- bined adjusting and'lockingmechanism which andA 'locking ymechanism shown in Fig. l. lThisform of the mechanism is similarfto that lshown in Fig. 'l except;thatitis so` constructed and arranged that when a brake application isinitiated the load adjustment will be made before any fluid underpressure is supplied to thebrakecylinder. y 'A's shown rin Fig. 2 of thedrawing this' mechanisrn'is'substantially the same as the mechanismshown in Fig. v1 and like parts in Aboth mechanisms are identified bylike numerals.. The only difference in construction lies in theprovision-of means for interlocking of thebrake cylinder device and thebrake cylinder supply and release .pipe 10 through the combinedadjusting and locking mechanism.A To accomplish such Vinterlocking thereis provided a seriesof ports 85 which extend from the interior ofthewbody portion 36 to a passage lformed in the wall thereowhich latterpassage is connected throughpipes 88 and a flexible hose 89 to the brakecylinder device.

-In the manner of arrangement it will be noted thatthe brake cylindersupply'and release pipe l is connected only t'o chamber 45 in theadjusting mechanism by way of the flexible hose 4l and pipe 46 and thatthe brake cylinder 5 is' isolated from such pipe 'l0 While the brakesare released. Operation of the combined'adjustiny and locking mechanismshown in Fig. 2

From the foregoingdescription ofthe mechanism shown'in Fig. 1 it will`be understood that' a slight increase in the pressure of fluid in thebrake cylinder supply and release pipe "Hl andconsequently in thechamber 45 of the adjusting mechanism/will cause the piston 38 to movedownwardly to its stopped position. It willalso` be understood thatmovement of piston 38 to thisy stopped positionwill adjustthe 'fulcrum'pin 26 relative to the brake cylinder leveri'l to provide for the degreeof `braking called for by the weight ofthe lading carried by thevehicle. Y v `When the piston-38 in this form ofthe adjusting mechanismhas been moved to its lowermost -or stopped position, the upper face ofthe piston `will be brought to a stop, justbelow the ports86 and thepassage 54. With the piston in this position, communication will beestablished between chambers 45 and 53 and also between chamber 45 andthe brake cylinder 5, the communication between chambers being made byway of passage 54 and between chamber 45 and the brake cylinder by Wayof ports 86, passage 8l, pipes 88 and hose 89.

With the communication between chambers 45 and 53 thus established fluidunder pressure supplied to chamber 45 flows to chamber 53 to effectlocking of the fulcrum pin 2B in the same manner as hereinbeforedescribed in connection with Fig. l. With the communication betweenchamber 45 and the brake cylinder established, in the manner abovedescribed, fluid under pressure in charnber 45 flows to the brakecylinder device which device functions to effect an application of thebrakes in the usual manner. i

To initiate a release of the brakes, fluid under pressure is vented fromthe brake cylinder pipe 1l) and consequently from the chambers 45 and 53to the atmosphere. Since the brake cylinder device is in opencommunication with the chamber 45 fluid under pressure will be ventedfrom the brake cylinder by way of pipes 88, hose 89, passage 81, ports85 and chamber 45. This venting of fluid under pressure from the brakecylinder device 5 and chamber 53 willv continue in the manner justdescribed until the pressure of fluid in chamber 45 has been reducedsufficiently to permit the spring 50 to return the piston 38 to theposition in which it is shown in thedrawing. With thepiston in thisposition,` the, final release of fluid under pressure from chamber53 tothe atmosphere is by Way of passage 54, chamber 49 and passage 85 andfrom the brake cylinder device 5 by Way of pipes 88, hose 89, passage`8l, ports 86, chamber 49 `and passage 85. i ,i

As hereinbefore 'described the release of uid under pressure from thebrake cylinder device 5, will effect a release of the brakes on thevehicle and the release of lluidunder pressure from the chamber `53 willeffect unlocking of the fulcrum lever 22 and thereby the fulcrum pin 25.With the brakes released and the fulcrum pin. 26` unlocked, the spring30v will return the fulcrum pin to the position in which it is shown inthe drawing if the vehicle is empty. If the vehicle is loaded thefulcrum pin will be returned to the position called for by the weight ofthe lading carried.

Having now described our invention, what we claim as new anddesire tosecure by Letters Patent is: i l

1. In a variable load brake of :the typecomprising a brake lever systemoperative to eect an application and a release of the brakes, incombination, a fluid pressure responsive brake. cylinder device foreiecting the operation of said .i

system, means associated with said system and operative for varying theleverage ratio of the system, a mechanism conditionable in accordance lwith the load carried by the vehicle and operative-upon an increase inbrake cylinder pressure for operating said means, and locking meanslcontrolled by said mechanism operative to lock said means in theposition to which lt has been actuated. y l

2. In a variable load brake of the typecomprising a brake lever systemoperative to'effect an application and a, release of the brakes,` in

combination, a fluid pressure responsive brake cylinder device foreffecting the operation of said system, means including a mechanismconditionable in accordance with the load carried by the vehicle andoperative by variations in the pressure of uid supplied to said brake4cylinder for varying the leverage ratio-of the system, `locking meansoperative to lock said means in any position to which it hasbeenactuated, and uid pressure responsive means controlled by said' meansand operativeby fluid under` pressure supplied to said brake .cylinderfor eiecting operation of said locking means.

3. In a vehicle variable load brakeof the type comprising a brake leversystem operative lto effect an application'and a-release of the brakes,

.in combination', a fluid pressure responsive brake cylinder devicecarried by an unsprung part of the vehicle for effecting the operationof said system,y means operative for `varying the` lever- Aage ratio ofthe system; means conditioned in accordance with the load carried by thevehicle and operative by the pressure of fluid supplied to said brakecylinder for actuating the first mentioned means, the last mentionedmeans being carried by a sprung vpart of the vehicle and having a lostmotion connection with the rst mentioned means to accommodate verticalmovement between said sprung and unsprung parts and to provide for theconditioning of the second mentioned means.

4. In a variable load brake apparatus for a vehicle of the type having axed part and a movable part said movablepart being constructed andarranged for vertical movement relative-to the nxedpart in `responsiveto variations in the Weight impesedgthereon, in combination, abrakelever operatively connected" to one end of a brake member'fto beoperateda brake cylinder connected. to said lever and operative upon anincrease" in fluid under pressure supplied thereto to actuate the leverand thereby said member, a slotted .opening'in said lever extendinglongitudinally of the lever intermediate its ends, afulcrum element forsaid lever disposed in said slotted opening, `rneans carried by saidfixed part of the vehicle forshifting said fulcrum element relative tosaid lever. and uid pressure responsive means carried by the movablepart of the vehicle and responsive to van increase yin brake cylinderpressure .for effectingy movement of said means.

l 5.` Inv a variable load brake apparatus for a vevhicleof the typehavinga xedpart and amovablev part said movable part constructed andarranged for verticalv movement relative to the xed v'part inresponsetoA variations ,in the Weight imposed thereon, in combination, a brakelever operatively connected to one endv of a brake member to beoperated, a brake cylinder connected to said lever'vand operative uponan increase in fluid under pressure lsuppliedtheretoy to actuate thelever andthereby said'mem'ber, a

vslotted opening in ysaid lever extending longitudinallyv of the leverintermediateits ends, a fullcrum element for said leverV disposed insaid slotted opening, adjusting means carried by said xed part to shiftysaid fulcrum element relative toA said lever, locking means operative tolock said adjusting means and `thereby said fulcrum' element in itsadjusted position, and fluid pressure responsive means carried byvthe/movable part vand vresponsive to an increase inv brake cylinderpressure for effecting the operation'of said adusti'ng means to shiftsaid fulcrum element for eiecting operation of said locking means tolock vsaidv adjustngmeans in the position to which it is ber to beoperated, va brake cylinder connected'v to said lever and operative uponan increase in Il uid under pressure supplied thereto' to actuate thelever and thereby said member, a slotted opening in said lever extendinglongitudinally of the lever intermediate'its ends,v a fulcrum elementfor said lever disposed in said slotted opening, apin carried by saidfixed part of the vehicle, a lever pivotally mounted at one end on saidpin and rockable .aboutthe pin for shifting said fulcrum elementrelative to said brake lever, and fluid pressure responsive mea-nscarried by the movable part of the vehicle and operative b-y an increasein brake cylinder pressure for rocking the fulcrum" shifting lever. f

'.7'.v In a variable .load brake apparatus for a vehicleof the typehaving a fixed part and a movable part said movable part beingconstructed and arranged"for vertical movement relative to thenx'edpartv in responseto variations in the weight imposedv thereon, incombination, a brake lever yoperatively` connected to one end of a brakememberfto'be operated, a braket cylinder connectedjto said lever andoperative upon an increasein flui'dun'der pressure' supplied thereto toactuate the lever and thereby said member,

aslotted opening in said lever extending longitudinally of the leverintermediate' its ends, a fulcrum element for said lever disposed insaid slotted opening, a pin carried by said xed part of the vehicle, alever pivotally mounted at one end on saidv pin and rockable about thepin for shifting said fulcrum element relative to said brake lever', atoothed' bar operatively connected to the opposite yend of said lever, aslidably mounted member for movementinto locking engagement with saidbar, and fluid pressure responsive means operative upon anincrease inbrake cylinder pressure for rocking said lever and for then actuatingsaid slidably mounted member into locking engagement With said bar. 8.In a variable load brake apparatus for a vehicle of the type having afixed part and movable' part said movable part beingv constructed andarranged for vertical movement relative to the fixed part inV responsevtoy variations in thev of the vehicle, a lever pivotally mounted at oneend onsaid pin and rfo'ckable about the pin for shifting said fulcrumelement relative to said brake lever, a toothed bar operativelyconnected to the opposite end of saidY lever, slidably mounted memberformovement into locking engagement With said bar, and uid pressureresponsive means operativeupon a relatively slight ncrease in brakecylinder pressure for rocking said 'lever and upon a predeterminedhigher increase in brake' cylinder pressure, for actuating said slidablymounted member into locking engagementy With said bar.

9. In a variable load brake apparatus for a vehicle' of the type havinga fixed part and a movable part, said movable' part `being constructedand arranged for vertical movement relative to the fixed part vin`response'torvariations in theweight imposed thereon, in combination, abrake lever operatively connected to one end of a brake member to beoperated, a brake cylinder connected to the other end of said brakelei/er to actuatethe lever and thereby said member, a slotted opening insaid lever extending longitudinally of vthelever intermediate its ends,a iulcrum element for said lever movably mountedin said slotted opening,fulcrum element adjustingfmeanscarried by said fixed part of the vehiclefor shifting said fulcrum relative to ,said brake lever, ay brakecylinder pipe normally' deplete' 4,of fluid under pressure and throughWhich'lluid under Apressure may be supplied toeiect operation of saidbrake cylinder, and iluid pressurefmeans responsive to an increase inthe pressurey of fluid in said pipe, to a value less than thatrequiredtoeffect operation of said brake cylinder; `for shiftingV said fulcrumadjusting means.

l0. `In a variable load brake apparatus for a vehicle of the type havinga4 nxed part and a movablel part vsaid movable part being constructedand arrangedfor vertical movement relativetol the fixed partin responseto variations in the Weight imposed thereon, in combination, a brakelever operatively connected to one end of a brake member to be operated,a brake cylinder connected to the other end of said brake lever toactuate the lever and thereby said member, a slotted'opening in saidlever extending longitudinally of the 'lever intermediate its ends, afulcrum element for said lever movably mounted in said slotted opening,fulcrum element adjusting means carried by said fixed part of thevehicle for shifting said fulcrum relative to said brake lever, lockingmeans for locking said' fulcrum element adjusting means in its adjustedposition, a brake cylinder pipe normally deplete of fluid under pressureand through which iluid under pressure may be supplied to effectoperation of said brake cylinder, and fluid pressure responsive meansoperative upon an increase in pressure of fluid in said pipe, to a valueless than that required to effect operation of said brake cylinder, forfirst shifting said fulcrum'adjusting meansand for then locking thefulcrum adjusting means in vits adjusted position;

` l1. In a variable load brake apparatus for a vehicle, a brake leveroperative for effecting an application of the vehicle brakes, a brakecylinder for actuating said brake lever upon a predetermined increase influid under pressure, an adjustable fulcrum for said lever having aposition for empty vehicle braking and being movable therefrom tovarious' other positions through a loaded'vehiclezone for providingloaded vehicle braking, means for normally maintaining said adjustablefulcrum'in the position for emptyvehicle braking,fluid pressureresponsive means for'positi'oning said adjust'- able fulcrum means insaid loaded vehicle zone in accordance With the load carried by thevehicle, said fluid pressure responsive means being operative by fluidunderv pressure at a pressure below said predetermined'degree, and acommunication common to said brake cylinder and fluid pressureresponsive means through which fluidv under pressure is suppliedsimultaneously to both the brake cylinder and the fluid pressureresponsive means.'

12. In a variable load brake apparatus for a vehicle, a brake leveroperative for eiecting an application of the vehicle brakes, a brakecylinder operative by fluid under pressure supplied thereto foractuating said lever, adjustable fulcrum means for said lever having aposition for empty vehicle Vbraking and being movable therefrom tovarious other positions' through a loaded vehicle zone for providingloaded vehicle braking, spring means for normally maintaining saidadjustable fulcrum in the position for empty vel hicle braking, alever'pivotally mounted on an. unsprung part of the vehicle truckoperative to position said adjustable fulcrum means in accordance withthe load carried by the vehicle, locking means for locking said leverand thereby said fulcrum in any adjusted position, and fluid pressureresponsive means operative by an increase in fluid under pressure forcontrolling the operation of said lever, .saidlocking means and thesupply of uid under pressure to said brake cylinder. 4 i

13. In a variable loadbrake apparatus for a vehicle, a brake leveroperative for eiiecting an application of the vehicle brakes, a brakecylinder operative by uidunderpressure supplied thereto for actuatingsaid lever, adjustable fulcrum'means Vfor said lever having a positionfor empty vehicle braking and being movable therefrom to van'ous otherpositions through'a loaded vehicle zone for providing `loaded vehicle'braking, spring means for normally maintaining said adjustable fulcrumin the position for emptyvehicle braking, and iluid pressure responsivemeans for positioning said adjustable fulcrum means in said loadedvehicle zone in accordance with the load carriedA by the vehicle, saidfluid pressure responsive means being operative upon an increase influid under pressure supplied thereto for first positioningsaidadjustable `fulcrum means and for then supplying uid under pressure tosaid brake cylinder.

14. In a variable load brake 'apparatus fora vehicle, a brake leveroperative for effecting 'an application of the vehicle brakes, a brakecylinder operative by fluid under pressure supplied thereto foractuating said lever, adjustable lfulcrum means forA said lever having aposition for empty vehicle braking and being movable therefrom tovarious other positions through a loaded vehicle zone for providingloaded vehicle braking, locking means for locking said adjustablefulcrum means in its adjusted position, a pipe through which fluid underpressure is adapted tobe supplied to said brake cylinder, and meansinterposed in said pipe and responsive to an increase in the pressure offluid in said vpipe for preventing the flow of fluid under pressure tosaid brake cylinder until after said adjustable fulcrum means ispositioned and locked in its adjusted position.

15. In a variable load brake apparatus for a vehicle of the type havinga` fixed part and a movable part constructed and arranged for verticalmovement relative to the xed part in responseto variations in the weightimposed thereon, in combination, a brake lever operatively connected toone end of a brake member to be operated, a brake cylinder connected tothe other end of said lever and operative upon an increase in uid underpressure supplied 'thereto to actuate the lever and thereby said member,a slotted opening in said lever extending longitudinally of the leverintermediate its ends, a ful- Crum element for said lever disposedv insaid slotted opening, means carried by said fixed part for shifting saidfulcrum element along said lever, and fluid pressure responsivemeanscarried .by the movable part and having a lost motion connectionwith the means for shifting said .fulcrum element, said fluid pressureresponsive means being operative by uid under pressure supplied to thebrake cylinder for actuating said means for shifting said adjustablefulcrum means only upon relative movementy between said xed and saidmovable parts of the vehicle,

16. In a variable load `brake apparatus Vfor a vehicle of the typehaving a fixed part and a movable part constructed and arranged forvertical movement relative to the fixed part in response to variationsin the Weight imposed thereon, in combination, a brake lever operativelyconnected to one end of a brake member tobe operated, a brake cylinderconnected to the other end of said lever and operative upon an increasein fluid under pressure supplied theretoto actuate the lever and therebysaid member, a slotted opening in said lever extending longitudinally ofthe lever intermediate its ends, a fulcrum element for said leverdisposed in said slotted opening, a lever pivotally mounted on saidfixed part of the vehicle for shifting said fulcrum element along saidbrake lever, fluid pressure responsive means carried by the movable partof the vehicle, said fluid pressure responsive means including a pistonand a stem operative relative to said'lever by uid under pressuresupplied thereto, and a. lost motion connection between said stem andsaid lever operative by movement of the piston and stem relative to thelever to `actuate said lever only upon relative movement between saidfixed and. said movablev parts of the vehiclel SIDNEY G. DOWN. Y CLYDEC. FARMER.

